At first, structure of a rectangular and thin type vibration motor employing the stepping motor, is explained.
FIG. 8a and FIG. 8b show a top view and a cross section taken on line A-A of FIG. 8a of a rectangular and thin type vibration motor employing the stepping motor used in the present invention, respectively (Similar prior art is disclosed in Patent Reference 4). A vibration motor 80 comprises a two pole flat stator 81 having a rectangle shape base block 87 and a housing 88, a rotor 82 consisting of a permanent magnet 82a locating in a rotor hole 81a provided on the flat stator 81, coupling magnetically with the flat stator 81 through a gap 81b and stopping with detent torque generated by notches 81c and 81d provided in the rotor hole 81a, a drive coil 83 coupling magnetically with the flat stator 81 and consisting of a coil 83b wound on a coil core 83a and a eccentric weight 85 secured to a rotor shaft 82b and functions as the vibration motor, as external power supply is supplied to a driver IC 86 in which a driving circuit is integrated to one chip, with an external power supply terminal (is not shown) which is able to be connected to the external power supply of the vibration motor 80, a bipolar drive current is supplied onto the drive coil 83, the rotor 82 is rotated at a high speed and a vibration is generated by a centrifugal force acting on the eccentric weight 85.
Next, FIG. 9a and FIG. 9b show a top view and a cross section taken on line B-B of FIG. 9a of another rectangular and thin type vibration motor employing the stepping motor used in the present invention, respectively (Similar prior art is disclosed in Patent Reference 4). The different point with the vibration motor 80 shown in FIG. 8a and FIG. 8b, is the point that for a rotor hole 91a of a two pole flat stator 91, not the notches 81c and 81d provided in the rotor hole 81a to generate detent torque, but steps 91c and 91d are provided in the rotor hole 91a. Because the structure except for it is the same with that of FIG. 8a and FIG. 8b, its explanation is omitted.
At first, using FIG. 3a and FIG. 3b that show a rotation chart of a rotor and a non-rotation and vibration chart of the rotor at a start pulse, respectively, the motion of the rotor 82 is explained when the vibration motor 80 shown in FIG. 8a and FIG. 8b is driven by the start pulse. One hand, as shown in the rotation chart of the rotor (FIG. 3a), when the rotor 82 is stopping, N and S of its magnetic poles 82a being along a M-M direction, the bipolar drive current is supplied onto the drive coil 83 from the driver IC 86 by the start pulse, the stator 81 is polarized to N and S along a L-L direction, the rotor 82 passes along 31a of a CW direction and a cross point 31b against the L-L and starts to rotate along 31c, on the other hand, as shown in the non-rotation and vibration chart of the rotor (FIG. 3b), when the rotor is stopping S and N of the magnetic poles 82a being along the M-M direction, the bipolar drive current is supplied onto the drive coil 83 from the driver IC 86 by the start pulse, the stator 81 is polarized to N and S along the L-L direction, and the rotor 82 passes along 32a of a CCW direction and a cross point 32b against the L-L and starts not to rotate but to vibrate along 32c and 32d. 
Furthermore, using FIG. 4 that shows a rotation control flow chart from power on until stop, is used, and the rotation control is explained. The rotation control becomes, on hand, as external power supply is supplied to the driver IC 86 (power on 41), start (42), start pulse output (43), goes to rotation detection (44) of the rotor 82, if the rotation of the rotor 82 is detected, goes to a start rotation mode (46), and the rotor 82 continues to rotate until the external power supply is turned off (power off 48), when the external power is turned off (the power off 48), the rotation control will stop (49), and again as the external power supply is supplied (the power on 41), the rotation control returns to start (42), and on the other hand, as at the rotation detection (44), the rotation of the rotor (82) is not detected, if try count is not over n (45), the rotation control returns to the rotation detection (44), if try count is over n (45) (in a drive pulse in a start non-rotation mode indicated in FIG. 1-(c) and FIG. 11-(c) explained hereinafter, n is set up 6, respectively) it goes to the start non-rotation mode (47), the rotor 82 continues to rotate until the external power supply is turned off (the power off 48), and when the external power supply is turned off (the power off 48), the rotation control will stop (49), and again as the external power supply is supplied (the power on 41), the rotation control is getting to the sequence that it returns to start (42).
Next, a conventional driving method and a conventional driving circuit of the vibration motor shown in FIG. 8a, FIG. 8b, FIG. 9a and FIG. 9b are explained (Similar prior arts are disclosed in Patent References 1, 2 and 3), using FIG. 12 that shows a block diagram of a conventional driving circuit, and FIG. 13 that shows a block diagram of a conventional rotor position detector with an operation amplifier, and FIG. 14 that shows a block diagram of a conventional rotor position detector with an inverter, FIG. 10-(a) that indicates a drive pulse, FIG. 10-(b) that indicates a voltage waveform after amplification, in a start rotation mode, FIG. 10-(c) that indicates a drive pulse, and FIG. 10-(d) that indicates a voltage waveform, in a start non-rotation mode and FIG. 11-(a) that indicates a drive pulse, FIG. 11-(b) that indicates an analog switching control signal of a reference voltage circuit for amplifier, in a start rotation mode, FIG. 11-(c) that indicates a drive pulse, and FIG. 11-(d) that indicates an analog switching control signal of a reference voltage circuit for amplifier, in a start non-rotation mode.
As shown in FIG. 12, the conventional driving circuit 220 consists of a rotor position detector 221 connecting to both terminals of a drive coil 226b of a stepping motor 226a shown in FIG. 8a, FIG. 8b, FIG. 9a and FIG. 9b and detecting a position of the rotor, a power on reset circuit 222 which when the external power supply is supplied to the driving circuit 220 connecting to an external power supply (is not shown) through an external power supply terminals 227a and 227b, outputs a motor control signal 222a that turns the motor on and as the external power supply is turned off, outputs the motor control signal 222a that turns the motor off, a reference signal generator 223 inputting the motor control signal 222a from the power on reset circuit 222 and generating a reference signal 223a, a drive pulse generation circuit 224 outputting a drive pulse 225a at timing of a rotor position detection signal 221a outputted by the rotor position detector 221 on the basis of the reference signal 223a from the reference signal generator 223, and as explained in details hereinafter, having a start rotation/non-rotation detecting means 224a and a start rotation/non-rotation mode switching means 224c inputting a start rotation/non-rotation detection signal 224b output by the start rotation/non-rotation detecting means 224a and a driver 225 which supplies a bipolar drive current to a drive coil 226b by the drive pulse 225a. 
The rotor position detector 221 consists of a reference voltage circuit 221b for amplifier, an amplifier 221e working on the basis of a reference voltage 221d output by the reference voltage circuit 221b for amplifier, a reference voltage circuit 221h for comparator which outputs a reference voltage 221i that is an intermediate voltage of the external power supply and a comparator 221g outputting a rotor position detection signal 221a to the drive pulse generation circuit 224 by comparing an output 221f of the amplifier 221e with the reference voltage 221i. 
As shown in FIG. 13, a conventional rotor position detector 230 using an operational amplifier comprises analog switches SW9 and SW10 connecting to external power supply terminals 238a and 238b and turning on or off by an analog switching control signal 237, resistors R31 and R32 connecting to the analog switches SW9 and SW10 and a reference voltage circuit 232 for amplifier connecting to a junction point 232a of the resistors R31 and R32 and consisting of a voltage follower 232b outputting a reference voltage 232c, an amplifier 233 consisting of an operational amplifier 233a with a feedback resistor R38, working on the basis on an output 232c of a voltage follower 232b through a resistor R36 and connecting to both sides of a drive coil 236 with driver terminals 236a and 236b through the resistors R36 and R37, a reference voltage circuit 235 for comparator connecting to a junction point 235b of resistors R33 and R34 connecting to the external power supply and the ground through external power supply terminals 238a and 238b and consisting of voltage follower 235c outputting a reference voltage 235d of an intermediate voltage between the external power supply and the ground and a comparator 234 inputting an output 233b of the amplifier 233 through a resistor R39, works on the basis of a reference voltage 235d that is output of the reference voltage circuit 235 for comparator through a resistor R40, consisting of a feedback resistor R41, inputting inversely an output 234b from a comparator 234a with hysteresis which is necessary to work exactly when an output 233b of the amplifier 233 gets across the reference voltage 235d and is product of ratio of the resistor R40 and a feedback resistor R41, and the external power supply value (Vcc) and consisting of an inverter 234c outputting a rotor position detection signal 234d. 
As shown in FIG. 14, a conventional rotor position detector 240 using an inverter comprises analog switches SW11 and SW12 connecting with external power supply terminal 247a and ground terminal 247b and turning on or off by an analog switching control signal 246, a reference voltage circuit 242 for amplifier consisting of resistors R51 and R52 connecting to analog switches SW11 and SW12 and connecting a junction point 242a of resistors R51 and R52 to the other terminal of a drive coil 245 with driver connection terminals 245a and 245b, an amplifier 243 connecting to the other terminal of the drive coil 245 through a resistor R53 and consisting of an inverter 243a with a feedback resistor R54, a comparator 244 consisting of inverters 244a and 244b inputting an output 243b of the amplifier 243 through a resistor R55, outputting a rotor position detection signal 244c, having a feedback resistor R56 and having the hysteresis which is necessary to work exactly when the output 243b of the amplifier 243 gets across a reference voltage (threshold) that is comparable with a reference voltage 235d of a reference voltage circuit 235 for comparator of the conventional rotor position detector 230 using an operational amplifier as shown in FIG. 13 and is product of, ratio of the resistor R55 and a feedback resistor R56, and the external power supply value (Vcc).
A conventional driving method is explained, using FIG. 10-(a) that indicates a drive pulse, FIG. 10-(b) that indicates a voltage waveform after an amplification, in a start rotation mode, FIG. 10-(c) that indicates a drive pulse, and FIG. 10-(d) that indicates a voltage waveform after amplification, in a start non-rotation mode, and FIG. 11-(a) that indicates a drive pulse, FIG. 11-(b) that indicates an analog switching control signal of a reference voltage circuit for amplification in a start rotation mode, FIG. 11-(c) that indicates a drive pulse, and FIG. 11-(d) that indicates an analog switching control signal of a reference voltage circuit of amplification, in a start non-rotation mode. Still, in the explanation, the stepping motor 80 shown in FIG. 8a and FIG. 8b, and a block diagram of a conventional rotor position detector using an operational amplifier in shown FIG. 13, are used, it is similar for the stepping motor 90 shown in FIG. 9a and FIG. 9b and a block diagram of a conventional rotor position detector using an inverter in shown FIG. 14.
To start the stepping motor 80, at first, a start pulse 101 with a chopper pulse 102 is output from the drive pulse generation circuit 224 shown in FIG. 12, by an analog switching control signal 101b that is an inverted non-pulse interval 101a of the chopper pulse, analog switches SW9 and SW10 of a reference voltage circuit 232 for amplifier shown in FIG. 13 are turned on, and a reference voltage 232c set up resistance division of the external power supply voltage according to resistances of R31 and R32, as an output of a voltage follower 233b becomes a reference voltage 114 of an operational amplifier 233a shown in FIG. 10, the reference voltage 114 is set up higher than an upper threshold voltage 113a of a reference voltage 113 that is an output 235d of a reference voltage circuit 235 for comparator, and in a timing diagram of a voltage waveform after amplification in a start rotation mode indicated in FIG. 10-(b), a counter electromotive voltage 107b of the rotor 82, indicated as a broken line, in the start rotation mode at the start pulse 101 gets over an upper threshold voltage 113a at a non-pulse interval 101a just before a chopper pulse 102, and at the non-pulse interval 101a, it is not detected that the rotor 82 has started to rotate, and at the next non-pulse interval 102a, a counter electromotive voltage 107b gets down from the upper threshold voltage 113a, and start rotation/non-rotation detecting means 224a which a drive pulse generation circuit 224 has detects the rotation of the rotor 82 through a rotor position detection signal 221a that a comparator 221g outputs, start rotation/non-rotation mode switching means 224c inputs a start rotation signal 224b which the start rotation/non-rotation detecting means 224a outputs, and then it goes to the start rotation mode, next drive pulse 103 in the start rotation mode is output by the drive pulse generation circuit 224, and the vibration motor 80 starts smoothly, on the other hand, in the voltage waveform after amplification in the start non-rotation mode indicated in FIG. 10-(d), as a counter electromotive voltage 124b in start non-rotation and vibration of the rotor 82 at a start pulse 115, indicated as a broken line, at non-pulse intervals 115a, 116a, 117a, 118a, 119a and 120a of chopper pulses 116, 117, 118, 119 and 120 gets over the upper threshold voltage 113a, the start rotation/non-rotation detecting means 224a which the drive pulse generation circuit 224 has, detects the start non-rotation and vibration of the rotor 82 through the rotor position detection signal 221a which the comparator 221g outputs, the start rotation/non-rotation mode switching means 224c inputs the start non-rotation signal 224b which the start rotation/non-rotation detecting means 224a outputs, and it goes to the start non-rotation mode, and the drive pulse generation circuit 224 in the start non-rotation mode outputs next wider drive pulse 121 than next drive pulse 103 of the start pulse 101 of the start rotation mode just after a non-pulse interval 120a, and the vibration motor 80 starts smoothly.
Patent Reference 1: Japanese Patent No. 3258125
Patent Reference 2: Japanese Patent No. 3645908
Patent Reference 3: Japanese Patent No. 3808510
Patent Reference 4: Unexamined Japanese Patent Publication No. 2007-104796